• Title/Summary/Keyword: Temperature Profile

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Influence of Thermodynamic Properties upon Transcritical Nitrogen Injection

  • Tani, Hiroumi;Teramoto, Susumu;Nagashima, Toshio
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.320-329
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    • 2008
  • The influence of thermodynamic transition associated with transcritical nitrogen injection upon the flow structure was investigated to explore numerical simulation of the injectant dynamics of oxygen/hydrogen coaxial jet in liquid rocket engines. Single and coaxial nitrogen jets were treated by comparing the transcritical and perfect-gaseous conditions, wherein the numerical model was accommodative to the real-fluid thermodynamics and transport properties at supercritical pressures. The model was in the first place validated by comparing the results of transcritical nitrogen injection between calculations and available experiments. For a single jet under the transcritical condition, the nitrogen kept a relatively high density up to its pseudo-critical temperature inside the mixing layer, since it remains less expanding until heated up to its pseudo-critical temperature. Numerical analysis revealed that cryogenic jets exhibit strong dependence of specific enthalpy profile upon the associated density profile that are both dominated by turbulent thermal diffusion. In the numerical model, therefore, exact evaluation of turbulent heat fluxes becomes very important for simulating turbulent cryogenic jets under supercritical pressures. Concerning the coaxial jets due to transcritical/gaseous nitrogen injections, the density profile inside the mixing layer was again affected by the thermodynamic transition of nitrogen. However, hydrodynamic instability modes of the inner jet did not show significant differences by this thermodynamic transition, so that further study is needed for the mixing process downstream of the near injection position.

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A Study on Temperature Profile and Residual Stress in Pipeline Repair Welding Using Sleeve (슬리브덮개를 이용한 배관 보수용접시 온도분포와 잔류응력에 관한 연구)

  • 김영표;김형식;김우식;홍성호;방인완;오규환
    • Journal of Welding and Joining
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    • v.14 no.5
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    • pp.95-105
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    • 1996
  • Korea Gas Corporation has operated high pressure gas transmission line of about 600 kilometers and, therefore, a series of repair welding processes are required in order to cope with external defects such as dent, gouge, cracking usually due to mechanical attacks. Most of gas pipelines repair processes are performed after completely venting remaining gas. However, in some case, though it is very unusual, repairs require without venting gas. For instance, this case is that damaged pipeline is remedied with split sleeve by welding. In this paper, in an effort to confirm a safe application of the split sleeve welding, residual stress, strain and temperature distributions are evaluated by computer simulation and experiments. The results obtained are as follows : 1) Computer modelling is supposed to be reasonable because microstructure changes due to welding is simulated coincidently as compare to that of real condition. 2) The maximal temperature on inside surface of pipeline is 50$0^{\circ}C$ for the repair welding process. 3) The amount of residual stress is estimated as the stress corresponding to 0.8% strain. 4) The repair process employed is determined to be technically preferable because of its avoiding cracks and fractures in the course of welding.

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Time dependent heat transfer of proliferation resistant plutonium

  • Lloyd, Cody;Hadimani, Ravi;Goddard, Braden
    • Nuclear Engineering and Technology
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    • v.51 no.2
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    • pp.510-517
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    • 2019
  • Increasing proliferation resistance of plutonium by way of increased $^{238}Pu$ content is of interest to the nuclear nonproliferation and international safeguards community. Considering the high alpha decay heat of $^{238}Pu$, increasing the isotopic fraction leads to a noticeably higher amount of heat generation within the plutonium. High heat generation is especially unattractive in the scenario of weaponization. Upon weaponization of the plutonium, the plutonium may generate enough heat to elevate the temperature in the high explosives to above its self-explosion temperature, rendering the weapon useless. In addition, elevated temperatures will cause thermal expansion in the components of a nuclear explosive device that may produce thermal stresses high enough to produce failure in the materials, reducing the effectiveness of the weapon. Understanding the technical limit of $^{238}Pu$ required to reduce the possibility of weaponization is key to reducing the current limit on safeguarded plutonium (greater than 80 at. % $^{238}Pu$). The plutonium vector evaluated in this study was found by simulating public information on Lightbridge's fuel design for pressurized water reactors. This study explores the temperature profile and maximum stress within a simple (first generation design) hypothetical nuclear explosive device of four unique scenarios over time. Analyzing the transient development of both the temperature profile and maximum stress not only establishes a technical limit on the $^{238}Pu$ content, but also establishes a time limit for which each scenario would be useable.

Numerical calculations for bioconvection MHD Casson nanofluid flow: Study of Brownian motion

  • Hussain, Muzamal;Sharif, Humaira;Khadimallah, Mohamed Amine;Ayed, Hamdi;Banoqitah, Essam Mohammed;Loukil, Hassen;Ali, Imam;Mahmoud, S.R.;Tounsi, Abdelouahed
    • Computers and Concrete
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    • v.30 no.2
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    • pp.143-150
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    • 2022
  • In this paper, the non-linear mathematical problem is solved via numerical scheme by utilizing shooting method. Brownian diffusion and thermophoresis along mass and heat transfer are accounted for. Non-linear expression is reduced via non-dimensional variables. The simplified ordinary differential equations are tackled by shooting technique. Behavior of distinct influential parameters is investigated graphically and analyzed for temperature and concentration profile. Our finding indicates that temperature profile is enhanced for the thermophoresis, Brownian motion coefficient, Prandtl number, Eckert number and temperature slip parameter. Comparison of numerical technique with the extant literature is made and an acceptable agreement is attained. Graphs are plotted to examine the influence of these parameters.

Mechanical texture profile of Hanwoo muscles as a function of heating temperatures

  • Chinzorig, Ochirbat;Hwang, Inho
    • Journal of Animal Science and Technology
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    • v.60 no.9
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    • pp.22.1-22.7
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    • 2018
  • Background: Cooking temperature and consequently doneness of beef muscles are most important for the palatability and consumer acceptability. Current study assessed the response of mechanical texture of Hanwoo muscles as a function of cooking temperature at different ageing days. Six muscles (Psoas major (PM), Longissimus thoracics (LT), Gluteus medius (GM), Semimembranosus (SM), Biceps femoris (BF) and Triceps brachii (TB)) were collected from each 10 Hanwoo steers. Warner-Bratzler WB-shear force (WBSF) and texture profile analysis (TPA) texture profiles were determined after 3 or 21 days of chiller, and randomly assigned to four groups; non-cooked, cooked at 55, 70 or $85^{\circ}C$. Results: Toughness of WBSF and TPA hardness of Hanwoo muscles were presence in the order of LT = PM = GM = SM < BF = TB (p < 0.001) for non-cooked raw muscle, and PM < LT = GM = SM < TB=BF (p < 0.001) for cooked meat aged for 3 days. WBSF linearly increased in 3 days aged meats after cooked at a higher temperature (P < 0.05). On the other hand, toughening of the muscles were significantly (P < 0.05) differed at various temperature when muscles were aged for 21 days. WBSF of PM and LT muscles were significantly increased at a higher cooking temperature, while other muscles (i.e., GM, SM, BF, TB) showed the lowest values at $70^{\circ}C$. In the case of TPA hardness, the effect of cooking temperature was very less in the toughness of the muscle (P > 0.05). Conclusion: Taken together, these findings clearly showed that the toughness of the muscle highly depends and varies upon the temperature and ageing of the muscle. Moreover, the effect of cooking temperature was very limited on aged muscles. The results mirror the importance of cooking temperature for objective measurements which ultimately estimate sensory tenderness and other quality traits.

Profile Simulation in Mono-crystalline Silicon Wafer Grinding (실리콘 웨이퍼 연삭의 형상 시뮬레이션)

  • 김상철;이상직;정해도;최헌종;이석우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.98-101
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    • 2003
  • As the ultra precision grinding can be applied to wafering process by the refinement of the abrasive. the development of high stiffness equipment and grinding skill, the conventional wafering process which consists of lapping, etching, 1st, 2nd and 3rd polishing could be exchanged to the new process which consists of precision surface grinding, final polishing and post cleaning. Especially, the ultra precision grinding of wafer improves the flatness of wafer and the efficiency of production. Futhermore, it has been not only used in bare wafer grinding, but also applied to wafer back grinding and SOI wafer grinding. This paper focused on the flatness of the ground wafer. Generally, the ground wafer has concave profile because of the difference of wheel path density, grinding temperature and elastic deformation of the equiptment. Tilting mathod is applied to avoid such non-uniform material removes. So, in this paper, the geometric analysis on grinding process is carried out, and then, we can predict the profile of th ground wafer by using profile simulation.

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Heat Conduction of the Solidification Process in a Cylinder with Finite Thichness (유한두께를 가지는 원형관내의 응고과정의 열전도)

  • ;;Ro, Sung Tack
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.1 no.4
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    • pp.196-202
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    • 1977
  • The solidification process in a cylinder with finite thickness in studied by explicit finite difference method. The temperature distribution, the solidification front profile and the dischrged latent heat for the process are obtained. It is found that the solidification front profile is almost linear except in the vicinity of the initation of phase change. This result motivates us to use linear relations between the position of solidification and time for approximate calculations.

THERMALLY DRIVEN BUOYANCY WITHIN A HOT LAYER DUE TO SPRINKLER OPERATION

  • Nyankina, K.;F Turan, O.
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 1997.11a
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    • pp.625-632
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    • 1997
  • A two-dimensional zone-like model is developed to predict the interaction between hot gas layer and water droplets after sprinkler activation. The model combines the motion equations for each droplet with heat and mass transfer between the gas and water. The results indicate that negative buoyancy in the hot layer can only be obtained if the initial temperature profile is uniform. If an experimental profile Is used instead, positive buoyancy results. This conclusion has been confirmed with experimental data.

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A Study on Pad Profile Variation Using Kinematical Analysis on Swing Ann Conditioner (스윙 암 컨디셔너의 기구학적 해석을 통한 CMP 패드 프로파일 변화에 관한 연구)

  • Oh, Ji-Heon;Kim, Yong-Min;Lee, Ho-Jun;Lee, Sang-Jik;Kim, Hyoung-Jae;Jeong, Hae-Do
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.47-48
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    • 2007
  • A CMP Process has many factors that affect result of a polished wafer. Dominant factors are velocity, pressure and temperature in process. A pad profile is also considered as affecting factor of CMP. Accoding to variation of a pad profile, the each pan of a wafer is differently pressured. It appears to affect the uniformity of a wafer. A pad profile varies as a swing arm conditioner which have been ordinarily used in industry. A swing arm conditioner has several sectors in its swing path. This study aims that a wafer get a good uniformity as swing arm conditioner's path on pad is analyzed and simulated. Through the simulation, tendency of pad profile after conditioning will be predicted and the result of simulation compared with the result of experiment. The optimized pad profile would be made by to vary swing arm's velocity on each sector. In order to maintain the optimized profile, conditioner design or swing arm's velocity should be changed and designed.

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Optimum Design of Multi-Stacking Current Lead Using HTS Tapes (고온초전도 테이프를 이용한 적층형 전류 도입선의 최적설계)

  • 설승윤;김민수;나필선
    • Progress in Superconductivity and Cryogenics
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    • v.3 no.1
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    • pp.35-39
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    • 2001
  • The optimum cross-sectional area profile of gas-cooled high-temperature superconductor(HTS) current lead is analyzed to have minimum helium boil-off rate. The conventional constant area HTS lead has much higher helium consumption than the optimum HTS lead considered in this study. The optimum HTS lead has variable cross-sectional area to have constant satiety factor. An analytical formula of optimum shape of lead and temperature profile are obtained. For multi-stacking HTS current leads, the optimum tape lengths and minimum heat dissipation rate are also formulated. The developed formulations are applied to the Bi-2223 material, and the differences between constant area, constant safety-factor, and multi-stacking current leads are discussed.

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